To cope with the exponential growth in wireless data traffic. it is anticipated that substantially denser deployment of base stations or wireless access nodes will be required in the future. The feasibility of a very dense deployment of wireless radio access nodes is predicated on the existence of a backhaul network that can provide high-data-rate transport for each individual access node in the network. From the point of view of maximizing capacity, optical-fiber-based backhaul solutions are probably the most desirable ones and are most suitable for new constructions. However, in existing buildings and infrastructure, the cost of installation of new fibers to every access node in a very dense network can be prohibitive.
An alternative to the fiber backhaul solution is the wireless sell-backhaul solution, where the same access spectrum is used to provide transport. With self-backhauling, an access node may serve not only its own assigned user equipments (UEs) in its vicinity but also its neighboring access nodes as a relaying node in order to route data towards and/or from an information aggregation node in the network. FIG. 1 illustrates a group of self-backhauling radio access nodes 100 that form a multi-hop mesh network. The access nodes 100 cooperatively route each other's traffic to and from an aggregation node 104 through wireless radio communication links 102. The routes that the traffic should follow are decided by a routing algorithm. In general, a network may contain more than one aggregation node and any number of access nodes.
A significant difference compared to a fiber network (or any other wired network) is that in the wireless network, different nodes transmitting at the same time can interfere with each other, leading to reduced data rates. A common way to keep interference at an acceptable level is to introduce fractional reuse, which means that not all nodes are allowed to transmit at the same frequency at the same time. Such fractional reuse is often in practice realized by dividing the available spectrum into frequency slots (i.e. subbands within the total system bandwidth), and ensuring that nearby nodes do not use the same frequency slot for transmission at the same time. Instead of frequency slots, the fractional reuse process may alternatively use time slots (i.e. each transmission frame is split into a number of short time intervals), with analogous results. A combination of both time and frequency slots may also be used by fractional reuse processes.
When slots are used in a network (which is henceforth referred to as a slotted network), a routing algorithm must not only determine which sequence of nodes traffic to a certain destination should follow, but also which slots should be used for each hop along the route through the sequence of nodes. Finding optimal routes is in general an extremely complex task and, in practice, reduced-complexity suboptimal routing algorithms have been used to reduce processing overhead. These reduced-complexity routing algorithms may result in suboptimal utilization of available resources of the radio access nodes, unnecessary delays in communication of traffic, and other avoidable limitations on quality of service provided to communications between source and destination nodes.
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.